Yaesu FT-902DM, Instruction Manual

Page: 14 / 55

\
"
"
The BLACK lead shoul d , preferably , run directly
t.o the negative terminal of the battery . Using the
car frame as a negative connection or connecting
the RED lead to a positive point such as the ig­
nition switch places the transceiver in the same
current path as noise-creating devices, thus fa iling
to take advan tage of the filtering action of the
b attery . The p ower cable should be kept away
fr om ignition wires and should be as short as
p ossible to minimize voltage drop and to provide
a low impedance path from the transceiver to
the battery.
B efore connecting the power cable to the trans­
ceiver, check the b attery voltage with the engine
running (battery charging) . If the voltage exceeds
1 5 Volts DC, the regulator should be readjusted
s o that the highest charging rate d oes not ex­
ceed 1 5 Volts. The transceiver should always be
switched O FF while the car engine is being started
to p revent voltage transients from damaging p ower
supp ly comp onents.
Width
::o
11-l. 511
W idth Control A ct ion
\
-10
\ \
I '
\
/
\
-20
\ /
I \!
If
j
11 I/ \
--
1'
'£
- 'L
\,
-•O
-.so
-60
- 2 - 1
(f
- -J.
R eject ion
Tun in g
Act ion
--
-
ANTENNA CONSIDERATIONS
The FT-9 02 transceivers are d esigned for operation
using an antenna system presenting a 5 0-7 5 ohm
resistive load at the antenna jack. Amateur instal­
lations seldom meet this requiremen t over the
entire spread of ever y band, b ut the final amplifi er
pi network is sufficiently forgiving to allow for
minor deviations from th e target figure . Ho wever,
signifi cant departures from the 5 0- 75 ohm range
will result in seriously degraded transceiver p er­
formance .
I f a n open-wire feedline i s used, o r if the input
impedance of the antenna. system presents a very
high or very low imp edance at the coaxial input ,
some sort of antenna tuner m u s t be u sed to pro­
vide a 5 0 - 7 5 O hm unbalanced feed point for the
transceiver.
For mobile operation, most of the commercially­
available antennas on the m arket will p rovide
good results if care is taken to tune the antenna
for minimum SWR . The outer conductor of the
coaxial cable should be securely grounded to the
automobile chassis at the antenna m ount.
-12-
10
0
-20
-30
10'
10 10
20 20
30
30
•o
50 5 0
60
- 2
-
l
Ci
to
..
1 •2
lSSB)(CW)
-2 -1 (f t- l T 2
SSB, CW
F ilters
fo=400Hz
fo=600Hz
103
'
Frequency(
Hz)
APF A ct ion
SSB
F ilter
fo-800Hz
10'
....